docs: def detect(self, root_device='/'):
          """
          Detect all currently known devices.
  
          :param str root_device: object path of root device to return
          :returns: root node of device hierarchy
          """
          root = Device(None, [], None, "", [])
          device_nodes = dict(map(self._device_node,
                                  self._mounter.get_all_handleable()))
          # insert child devices as branches into their roots:
          for node in device_nodes.values():
              device_nodes.get(node.root, root).branches.append(node)
          device_nodes['/'] = root
          for node in device_nodes.values():
              node.branches.sort(key=lambda node: node.label)
          return device_nodes[root_device]